It is proposed to study the function, structure, electrophysiology and pharmacology of identified aminergic and peptidergic neurons in the locust, cockroach and related species of insects. An important objective is to develop model simple systems in which the precise site and mode of action of biogenic amines and peptide neurotransmitters can be determined. It is likely that this investigation will yield concepts and methods which will aid our understanding of modulatory neurotransmitters in the mammalian nervous system. Histofluorescent methods will be perfected which allow for the localization of octopamine in identified octopaminergic neurons. This technique will then be employed in the localization of octopamine in the mammalian CNS. Immunological, biochemical, and intracellular electrophysiological techniques will be combined to characterize nurotransmitters, locate receptors and to investigate functions and physiology of identified aminergic and peptidergic neurons. The hypothesis that the amine and peptide containing neurons are involved in modulation of synaptic function, possibly mediated by intracellular second messengers, will be tested.